Re: [PATCH v9 12/27] KVM: x86: Report XSS as to-be-saved if there are supported features

From: Chao Gao
Date: Thu Jan 25 2024 - 05:38:28 EST


On Tue, Jan 23, 2024 at 06:41:45PM -0800, Yang Weijiang wrote:
>From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
>Add MSR_IA32_XSS to list of MSRs reported to userspace if supported_xss
>is non-zero, i.e. KVM supports at least one XSS based feature.
>
>Before enabling CET virtualization series, guest IA32_MSR_XSS is
>guaranteed to be 0, i.e., XSAVES/XRSTORS is executed in non-root mode
>with XSS == 0, which equals to the effect of XSAVE/XRSTOR.
>
>Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
>Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
>Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>